Defibrotide is a polyanion salt of a deoxyribonucleic acid obtained from mammalian tissue. Defibrotide is a single-stranded polydeoxyribonucleotide with molecular weight of approximately 20 kDa (low molecular weight form) which may be obtained from bovine lung DNA by controlled hydrolysis. Patents related to its manufacture include U.S. Pat. No. 3,770,720 directed to a process for extracting DNA from mammalian tissue, and U.S. Pat. No. 3,899,481 directed to a process for the controlled partial degradation of DNA extracted from animal organs.
Experimental studies have been performed to investigate the active component of defibrotide. U.S. Pat. No. 3,770,720 discloses that the components of defibrotide include phosphorus 8.5%, Na 9.0%, N 14.0%, deoxyribose 23.2%, total bases 34.0%, guanine 9.4%, thymine 9.4%, adenine 9.2%, cytosine 6.0%, uracil absent, Iodine, and Zinc.
Bracht et al., (Biochem. and Biophys. Res. Com., vol. 200, No.2, 1994, pp.933–937) have disclosed four apatamer sequences derived from the unfractionated defibrotide DNA precursor molecule. Two aptamers (5′-GGTTGGATTGGTTGG-3′ (SEQ ID NO: 1) and 5′-GGTTGGATCGGTTGG-3′ (SEQ ID NO:2)) were identified by thrombin chromatography. Another apatamer (5′-GGATGGATCGGTTGG-3′ (SEQ ID NO:3)) was found in the PCR product from the double-stranded DNA precursor. The sequence of such apatamer was used to search the EMBL data base and was found in the bovine genome and Angiotensin II-AT1 receptor. The three aptamers were found to have inhibitory activities of thrombin induced platelet aggregation, thromboxane biosynthesis, increase in cytosolic Ca++, and fibrin clot formation. In addition, there is a non-function apatamer (5′-GGTGGTGGTTGTGGT3′ (SEQ ID NO:4)) which did not display any of the activities characteristic of defibrotide.
HIV infection is characterized by a progressive decline in immune system function, suppressing the infected host's ability to overcome other, secondary infection. No cure has been found for HIV infection. The pathogenetic process in HIV infection is never unidimensional but, rather, extremely complex and multifactorial. The pathogenic progression may be only tangentially related to the direct infection of a given target cell. Death is almost inevitable, usually from an overwhelming secondary infection and/or HIV related neoplasm.
Current treatments for HIV infection attempt to retard the progress of the disease or relieve its symptoms. Treatment in use today include certain dideoxynucleotides such as azidothymidine (AZT or zidovudine, Burroughs Wellcome), dideoxyinosine (ddI, Bristol-Myers Squibb) or dideoxycytidine (ddC, Hoffman-LaRoche). These agents can be toxic. Their applicability is limited because of the appearance in some patients of onerous, and sometimes lethal, side effects. These side effects include myelosuppression, peripheral neuropathy, and pancreatitis. In some patients, AZT has lost its effectiveness after prolonged use. While other drugs have been proposed for treatment of HIV infection, including the recent introduction of several HIV protease inhibitors, none have yet been demonstrated to be completely effective. Therefore, there remains a need in the art to develop additional therapeutic agents to treat HIV infection. In particular, there is a need in the art to further identify the active components of defibrotide and their applications in various disease conditions.